The bee’s unusual social structure has allowed biologists to collect some of the best evidence yet that living in a society can boost brain size – NewScientist (mag article)

Many evolutionary biologists believe the increased in the size of the brain relative to the body size in animals such as primates was driven by the demands of living in societies. This is known as the social – or Machiavellian – intelligence hypothesis.- Previous comparisons of different birds and primates have shown that more social animals tend to have larger brains. - “Social interactions seem to impose important cognitive challenges that must be met by enhanced investment in certain brain regions”